#OTD in 1743.
French physicist Jean-Pierre Christin published the design of a mercury thermometer using the centigrade scale with 0 representing the melting point of water and 100 its boiling point.
Available at : Annales des sciences physiques et naturelles, d'agriculture et d'industrie
By Société d'agriculture, sciences et industrie de Lyon. via @googlebooks
In his paper Observations of two persistent degrees on a thermometer, Christin recounted his experiments showing that the melting point of ice is essentially unaffected by pressure. He also determined with remarkable precision how the boiling point of water varied as a function of atmospheric pressure. He proposed that the zero point of his temperature scale, being the boiling point, would be calibrated at the mean barometric pressure at mean sea level.
Historical note:
1742 Anders Celsius invented the Celsius temperature scale. In its original form the scale had 0 degrees for the boiling point of water and 100 degrees for its freezing point.
1743 The scale was changed by Jean Pierre Christin so that 0 degrees is the freezing point of water and 100 degrees is its boiling point.
via @internetarchive
Anders Celsius published his research at Abhandlungen über thermometrie, von Fahrenheit, Réaumur, Celsius, (1724, 1730-1733, 1742)
Hrsg. von A.J. von Oettingen.
Available via @internetarchive
